I don't use line wrapping because it breaks long URLs. If that makes
you or your e-mail client cringe, you may as well read this at
http://bufferoverflow.tiddlywiki.com instead (same text, nicer
formatting).

First of all, let me thank all of you who responded. As promised, I am
giving feedback to the list so that future purchasers of Western
Digital WD EARS/EADS models and similar "Advanced Format" hard drives
may benefit.

The first thing of notice is that the Load_Cycle_Count of the drive
heads increases every 8 seconds by default. As seen on the Internet,
this may pose a problem in the long run, since these drives are
"guaranteed" to sustain a limited number of such head parking cycles.
The number given varies from 300.000 to 1.000.000, depending on where
you look. The first thing I did was, therefore, launch a shell script
that wrote something to the drive every second. Not being content with
this dirty workaround, I proceeded to download the WD proprietary
utility wdidle3.exe, and the first link obtained by googling for
"wdidle3.exe" did the trick:
http://support.wdc.com/product/download.asp?groupid=609&sid=113I then proceeded to download a freedos bootable floppy image and copied
it to a floppy disk using dd. Once the bootable floppy was thus
created, I copied wdidle3.exe thereto.
Reboot computer, change BIOS boot order to floppy first, save&exit, the
floppy boots and I run wdidle3.exe. The utility offers three
command-line switches, for viewing the current status of the
Load_Cycle_Count parameter, for changing it, and for disabling it. No
drive is specified, so if you change/disable the parameter, you are
doing this to ALL and ANY WD drives in your system. I chose to disable
head parking, and since I also have an older 160GB WD IDE disk in the
box, the utility disabled head parking cycles for BOTH drives.
Except that ... there be problems. As opposed to the old 160 GB drive,
the setting didn't work for the new 2 TB drive. Instead, the frequency
of the load cycles increased 16-fold, to a whopping 7200 cycles per
hour! This quickly increased my Load_Cycle_Count parameter (checked by
issuing smartctl --all /dev/sda) by several thousand ticks overnight.
Interestingly enough, the drive loaded and unloaded its heads at the
amazing rate of twice per second even while sustained copying was
underway (copying a 10 GB directory subtree from one drive to another).
I didn't notice the increased cycle count until the next morning,
however. When I did, I rebooted the machine with the freedos floppy
again and set the interval from "disabled" to "every 300 seconds",
which appears to be the maximum interval allowed. It would seem that,
for the time being at least, this made the Load_Cycle_Count stay put at
22413. Whew!
So, setting this bugger straight is probably the first thing you'll
want to do after getting one of these WD drives.

Now, the second issue: the hardware/logical sector alignment.

Since it will affects real-world transfer speeds, let's first check out
the theoretical speeds of this drive in this particular environment --
a 3GHz Pentium-IV motherboard with a humble integrated SATA controller
(I think it's an early SATA-I generation).

Anyway. I have to prepend here that, Squeeze still not having reached
stable, all of the following was performed on a stock Lenny i386 system
(the reason being I have no Squeeze system yet). So, many of the
following points may become obsolete in a matter of weeks when Squeeze,
with a newer kernel and updated partitioning tools, reaches stable.
The first thing is, fdisk in Lenny doesn't support GPT partitioning, so
I had to use parted. I first used its Gnome variant, GParted, and must
say that it cant't align the partitions. Even if you align the first
sector by hand (in parted, since GParted can't do it) and de-select the
"Round to cylinders" option in GParted as recommended in
http://www.ibm.com/developerworks/linux/library/l-4kb-sector-disks/index.html(which was my main guide and reference in this adventure), GParted will
end your partition on an aligned sector -- which means that, by
default, the next partition will start on a non-aligned sector again.
Be as it may, I then proceeded to use the new partitions created by
GParted, doing some cursory "benchmarks". The typical copy speed
reached in mc was about 20 MB/s, while rsync reported speeds of up to
51MB/S. Rsync reached a maximum 51MB/s on unaligned partitions, when
copying from hda (WD1600AAJB) to sda (WD20EARS).

Then I tried to re-align my partitions by manually calculating the
starting sectors of all the partitions so as to have them divisible by
8. This could only be done in parted, not in GParted. On the other
hand, parted couldn't create ext3 filesystems, so manually created
partitions had to be subsequently formatted in GParted. In short, a
combination of both tools had to be used to successfully create AND
format the partitions. Here's my final result as seen in parted (fdisk
doesn't understand GPT):

I was just curious if aligned partitions would yield any noticeable
speed improvement (especially in the file write department, since file
reads, according to the above IBM article, should not be that heavily
hit by misalignment). The "benchmarks" I performed, consisting in
copying random files from the other drive to the WD20EARS using mc and
rsync, generally yielded something between 15 and 35 MB/s, sometimes
falling under 10 MB/s and at times going as high as 56 MB/s; the latter
figure, however, was usually reached in the initial moments of a large
file rsync (an Ubuntu CD ISO file) and would decrease after several
seconds to about 40 MB/s, so it may very well be due to the 64MB cache
on these drives. Just for the heck of it, I decided to re-align the
partitions modulo-64, thus:

Partition Table: gpt

Number Start End Size File system Name
Flags
1 128s 8194047s 8193920s linux-swap
linux-swap 2 8194048s 49154047s 40960000s
ext3 ext3 3 49154048s 90114047s
40960000s ext3 ext3 4 90114048s
1998569472s 1908455425s ext3 ext3 5
1998569473s 3907024064s 1908454592s ext3
Rsyncing the good old ubuntu ISO file yielded transfer rates of around
60 MB/s, with the exception of the last partition, which was written to
at under 50 MB/s. It made me wonder. I checked the mount options in
fstab, double checked that the CPU governor was set to max performance,
all to no avail. Then, I fired up parted again and noticed that the 5th
partition was actually one sector off. I corrected my error thus:

By default, these WD drives are not Linux-ready. They do work
out-of-the box, but are not configured optimally speedwise. Given that
we're talking about "green" (marketing mumbo-jumbo for "slow") drives,
this additional performance hit is noticeable and quite undesirable. By
aligning the partitions on 8-sector boundaries, the transfer speeds are
improved by almost 20%; aligning them on 64-sector boundaries doesn't
yield further noticeable improvements though. Or, more precisely: the
tests I performed were too coarse to substantiate potential small
differences, because as differences become smaller, other factors, such
as the CPU governor used, fstab parameters, or actual load on the CPU
at a given moment may prevail, completely masking such small
differences. The CPU governor seems to be the most crucial of those
secondary factors (see below). So, there are indications that using
64-sector alignment "may" give a slightly better performance over
8-sector alignment, but they are nothing more than indications, really.
Proper benchmarks would be required to ascertain that.

Curiosa:

All testing was done with a ~700-MB ISO file; copying many smaller
files may (and will) incur additional performance hits.
Dropping the CPU governor to powersave reduced file writes to under 20
MB/s and less, which means to about a third of the maximum speed
achievable.
Mount options for the partitions, and the performance of the source
disk are also major factors in these tests. In my case, the source from
which the files were copied was an oldish 160 GB WD IDE drive (model
WD1600AAJB).
The only downtime needed was about 10 minutes -- the time it took to
actually install the drive into the chassis; had WD provided a tool for
online modifying the drive's S.M.A.R.T. Load_Cycle_Count parameter, no
further reboots would be needed, i.e. once the hard drive was
installed, it could be taken to production use without as much as a
single reboot. Due to my own mistake, however, a superfluous reboot was
needed. Namely, while messing with parted and gparted and modifying
partition sizes, at one point I forgot to unmount the partitions before
deleting the partition table in parted. After that, I kept getting the
warning that a reboot would be required for the kernel to re-read the
partition tables, preventing me from creating the last two filesystems
and wrapping it up. Neither umount nor swapoff would help. Instead of
digging for the offending process and killing/restarting it, I
preferred to reboot the system, since it wasn't in use at the moment
anyway.
Beside the physical installation of the drive in the chassis, which was
done during off hours, virtually everything else was done remotely via
ssh, without interrupting the work of the currently logged-in user. To
enable graphical tools such as GParted to be used, ssh was run with the
-XC option, and then GParted was launched remotely by issuing "gksu
gparted". The flexibility of GNU/Linux is simply mind-boggling.
I have no kind words for WD. Their drives as provided are severely
underoptimized for GNU/Linux. On the drive label and on their site they
state that no further configuration is required for using the drive in
Linux; which is quite simply untrue. In addition, the head parking
feature is heavily flawed, and is only accessible via a DOS proprietary
tool, and only by taking the entire system offline. I am quite
disappointed in WD, but am thoroughly confident that the GNU/Linux
community will provide for the WD's shortcomings, as always. We'll see
what hdparm and smartmontools in Squeeze will bring along. The Lenny
versions are too old to be of much use with this disk (for example, the
hdparm -B command doesn't work).
The foregoing user experience is nothing more than that -- a user
experience; copying a handful of files is not to be considered a "test"
or "benchmark" in any meaningful sense whatsoever, so take it with a
huge lump of salt!